Preparation and study of plastic compounds containing polyolefins and post used newspaper fibers

A new process for the incorporation of old newspaper fibers into polyolefins, such as LDPE, HDPE and PP, was developed based on the dispersion of paper fibers in a hot polymer solution and the subsequent precipitation of the polyolefins by cooling, which produces a slurry of polymer with paper fibers. The technique studied in this work is an alternative to the conventional melt compounding and was expected to provide efficient wetting of fibers by the polymer. The density, hardness and tensile properties of composite specimens prepared by compression moulding, with filler content ranging from 10% to 40% (w/w), were measured. The tensile strength of HDPE and PP composites presents a slight decrease at filler concentrations between 10% and 20%, followed by considerable decrease in the range of 30–40%. On the other hand, the modulus of elasticity did not display a clear dependence on filler content. Composites based on LDPE showed good retention of tensile strength especially at low filler content, whereas their modulus of elasticity at 40% fiber concentration, increased by 78%.